Penal institutions frequently house inmates in dormitory-like cells or rooms which open to a common hall or corridor. In a prison environment it is, of course, mandatory that access to the cells by the inmates be controlled. It is desirable that such control be achieved either locally at each door or remotely from a secured central control room.
While previously known systems have attempted to provide such features, they have failed to achieve wide-spread acceptance due to a number of shortcomings such as technical complexity, functional inadequacy and high cost. For example, light weight electric solenoid bolt control devices have been previously proposed, such as the device disclosed in U.S. Pat. No. 3,893,723, wherein a bolt was actuated by a slide member 10 which moved between upper and lower solenoids. The device was unsatisfactory for high security installations since it was easily damaged by any substantial force applied to the bolt in its extended position. Any such force created a bending force on the solenoids and typically resulted in severe damage or destruction of the locking mechanism. The inmates' well known propensity for vandalism in penal institutions therefore rendered the device of this patent totally unsatisfactory for penal institution use.
Other penal door locking systems were not usable with conventional steel door jambs and door assemblies. The cost of custom door installations made such systems too expensive to be practical for use in government built penal institutions.
Other devices such as that shown in U.S. Pat. No. 1,946,384 have employed solenoid operated bolt members actuated by a pin and slot camming arrangement of complex construction suitable only for light duty in window sashes or the like.
U.S. Pat. No. 4,099,752 disclosed a lock in which an actuating solenoid for the bolt was mounted so that its plunger had an axis of movement perpendicular to the axis of movement of the lock bolt. The lock bolt also included a detent switch which energized a solenoid to lock the bolt when the door was closed.
Therefore, it is the object of the present invention to provide a new and improved door locking system for penal or similar institutions that is secure and relatively inexpensive to install.
It is yet another object of the present invention to provide a new and improved door locking system that can be operable from a remote site and from a position adjacent the door.